Intervertebral cages for spinal fusion help maintain disc space height, assist in the anterior column support of the spine, facilitate the fusion process due to the ability to hold bone graft in place and contribute to the overall alignment of the spine.
Several types of cages are used today through different surgical approaches. Several known techniques are used for fusion of the thoracic and lumbar spine. For example, cages for posterior or lateral approach are basically fixed spacers made out of titanium alloys or PEEK (polyether ether ketone) with chambers for bone graft location. They are usually rectangular in shape to be positioned in the disc space after discectomy. Regardless of the surgical technique, the intervertebral cage must be located inside the disc space in contact with the end plates preferably near the apophysial ring. Expandable cages are also known.